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Topic 3 Revision ­ Energy Flow

Plant and animal cells are similar
b ecau se
they cont
a i
n nuclei,
cytoplasm an d
a membrane.
Plant cells als
o
ha ve cellulose cell walls,
chloroplasts cont
a i
ning chlorophyll and
a vacuole.
A cell that is found in…

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Conditions for optimum growth are with all three variables at a medium level. These factors are known as limiting
factors.

Light intensity:
Increased light intensity increases rate of photosynthesis until the rate levels off, until then light is the limiting
factor after that another factor is in short supply.

Reducing…

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The Carbon Cycle (
incl
udi
ng
the
rol
es
of
)
Microorganisms
Photosynthesis
Respiration
Combustion















CARBON DIOXIDE: Recycled in the environment.
Combustion and respiration add carbon dioxide to the environment.
PHOTOSYNTHESIS: Removes carbon dioxide from the environment.

The Importance of Nitrogen in the Environment (including the roles of)
Nitrogen…

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DENITRIFYING BACTERIA: Converts nitrate into nitrogen gas.

Could a Biosphere be used to Colonise Mars?
Biosphere II was built in America in 1989. Scientists wanted to find out if humans and other living things could live i
Biosphere II without any help from the outside world. If the experiment worked,…

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Why are rainforests being destroyed?
Farming of cattle
Planting crops
Providing fuel
Clearing for building, houses or roads
Timber
Impact of Deforestation on the Environment:
Loss of habitat /places to live
Atmospheric CO2 levels increase (from burning/rotting/reduced photosynthesis), increased global
warming/greenhouse effect
Increases soil erosion/increased leaching of minerals/nutrients
Increases desertification…

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